Study Sees Pfizer Smoking Drug Risk

Hundreds of patients taking Pfizer Inc's anti-smoking drug Chantix have reported serious accidents, vision problems and heart trouble, researchers said on Wednesday, sending shares of the world's largest drugmaker to their lowest level since 1997.

U.S. aviation regulators responded quickly to the research,
saying they would prohibit use of Chantix by private and
commercial pilots, while consumer advocates called for stronger
warnings on the drug's label.

Chantix, also known as varenicline, has already been linked
to depression and suicide, among other problems.

Researchers at the nonprofit Institute for Safe Medication
Practices, and Wake Forest University, said they found hundreds
of reported problems since the drug's 2006 approval that
included blurred vision, dizziness, confusion and loss of
consciousness.

"These data provide a strong signal that the risks of
varenicline treatment have been underestimated and show that a
wide spectrum of serious injuries are being reported in large
numbers," the researchers said.

The data does not definitively prove that Chantix is at
fault but does show a strong signal, the researchers cautioned,
adding that the U.S. Food and Drug Administration and Pfizer
should take further steps, including conducting more studies.

Pfizer officials defended Chantix, one of the struggling
drugmaker's newest medicines, saying the side effects are
already mentioned on the drug's label.

"When you've got the nicotine withdrawal along with
Chantix, it's just very difficult to tell what is causing it,"
said Gretchen Dieck, Pfizer's senior vice president for safety
and risk management.

Chantix works by targeting brain receptors affected by
nicotine, tobacco's addictive ingredient. The drug blocks some
of the effects of nicotine while also providing a nicotine-like
buzz to help curb withdrawal.

Shares of the drugmaker fell 1.2 percent to $19.76 in
after-hours trading Wednesday following release of the study,
having closed on the New York Stock Exchange down 4 cents at
$20.01.

Sales Hurt

Pfizer has touted Chantix as one of its biggest hopes for
future earnings growth, but its sales have been hurt in recent
months by safety concerns.

In February, the FDA warned about the risk of mood and
behavior changes with Chantix and called for new warnings on
the drug's label. It also said the drug could impair patients'
ability to drive or use heavy equipment.

The drug brought in $277 million in U.S. sales during the
first quarter of 2008, but has since seen its prescriptions
fall 5 percent, according to Bear Stearns analyst John Boris.
On Monday he revised his estimate for 2008 sales to $640
million, down from $915 million.

But Morningstar analyst Damien Conover said the new data
was not surprising, given that many smokers have multiple
health problems.

Conover said many smokers might accept the risks for a
better chance to quit smoking, which can cause lung cancer and
other health problems. He said Chantix should still bring in
global sales this year of $1 billion.

FDA spokeswoman Susan Cruzan said the FDA was still
investigating the drug's psychiatric effects. Wider reviews of
new drugs like Chantix were desirable but "FDA currently does
not have adequate staffing to conduct such reviews."

Brain Receptors

The same brain receptors targeted by Chantix also control
muscle movement, according to the researchers, who combed FDA
data on reported side effects.

They found 173 reports of accidents and injuries in people
taking Chantix. They also found 397 cases of psychotic behavior
and another 227 involving suicidal behavior.

Hundreds of cases of severe skin swelling, heart problems
and diabetes were also reported.

The Federal Aviation Administration said 150 pilots and 30
air traffic controllers used Chantix, but it was unclear how
many of the pilots worked for airlines.

While the FAA was not aware if any accidents linked to use
of the drug, "it's prudent to deem the drug no longer
acceptable for use," agency spokesman Les Dorr said.

The new study prompted the Health Research Group of
consumer advocacy group Public Citizen to call for stronger
"black box" warnings on the drug's packaging.

(Additional reporting by Ransdell Pierson in New York and John
Crawley in Washington; Editing by Tim Dobbyn)